Problem: Solve for $x$ : $x - 5 = 21$
Solution: Add $5$ to both sides: $ \begin{eqnarray} \\ x - 5 &=& 21 \\ \\ {+5} && {+5} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{-5 + x} &\hphantom{=}& \hphantom{21} \\ x &=& 21 {+ 5} \\ \end{eqnarray} $ Simplify. $ x = 26$